Abu Dawud
Purification (Kitab Al-Taharah)
Book Number: 001 / Hadith Number: 126
Narated By Ar-Rubayyi' daughter of Mu'awwidh ibn Afra' : The Messenger of Allah (pbuh) used to come to us. He once said: Pour ablution water on me. She then described how the Prophet (pbuh) performed ablution saying: He washed his hands up to wrist three times and washed his face three times, and rinsed his mouth and snuffed up water once. Then he washed his forearms three times and wiped his head twice beginning from the back of his head, then wiped its front. He wiped his ears outside and inside. Then he washed his feet three times.
Abu Dawud said: The tradition narrated by Musaddad carries the same meaning.